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Relationship between different units used in civil engineering in Nepal

 Relationship between different units of plot area in Nepal

 

1 Aana

31.80 m2

 

342.25 sq ft

 

4 paisa

 

16 Dam

1 paisa

4 Dam

1 inch

2.54 cm

1 Ropani

16 Aana

 

64 Paisa

1 Bigha

20 Katha

 

13.31 Ropani

1 acre

1.613 Bigha

 

7.95 Ropani

1 Hectare

2.4711 Acre

1 Ropani

1.5 katha

1 Katha

20 Dhur

1 Haath

 1.5 feet

 



We often get confused between the feet and foot. But there is not vast differences between feet and foot. They both are used to measure the lenth of particular object. Foot meanings to the single unit of measurement, while feet is its plural form.

Also, If we use measurements as an adjective then, we use foot. If not then feet.

Example : There was a 6 foot road. The road was 6 feet in width.  

 

 

Relation between weight measurements used in Nepal

 

1 Metric ton ( tonnes )

1000 kg

1 Quintal

100 kg

1 kg

2.20462 pounds

1 pau

199 gram

Hence, 1 Kg

Approximately, 5 pau

1 Dharni

12 pau

 

2.39 kg

 

Floor Area Ratio And Setback distance

         

The ratio of the permissible built-up area (or floor area) of the building to the area of the plot in which the building is about to be built is called the floor area ratio (FAR).

      FAR = Total built-up Area ( B + C ) / Plot Area ( A)

 


Here, the sky blue color represents our total plot area.

Key Point: Balcony area does not get included in the total built up area. Only the area surrounded by walls is considered in the total built-up area.

For example : If the plot area is 1000 sq ft, and if the FAR is 1.75, then the total permissible floor area for the building is 1.75 * 1000 = 1750 sq ft. Total permissible built up area is 1750 means, the integration of the total floor area should be 1750. If we wish to build 2 story building of total permissible built up area of 1750 sq ft then, if we have taken the floor area of ground floor area as 1500 sq ft then the floor area of first floor should not exceed 250 sq ft (i.e. 1750- 1500 )  

If we wish to have 3 story building of permissible built-up area of 1750 sq ft, then the foor area of the ground floor + floor area of firrst floor + floor area of second floor <= 1750 sq ft.  



For FAR=1

1000*1= 1000 sq ft

This means we can build a building of area 1000 sq ft. Hence, we can either build a building of one story having area of 1000 sq ft, or we can build a building of 2 story, each story having a area of 500 sq ft, or we can build a building of 4 story having area of each story as 250 sq ft, and so on..





FAR is already fixed by government for particular city or area.

In kathmandu, previously FAR was 1.75, but according to Building Bye Laws, KMC published in 2018, allowable floor area ratio in kathmandu is 3.5.

FAR as defined by Kathmandu Municipality are:

Building Type

FAR

Residential building

3.5

School, College and University

2.5

Star Hotels

3.5

Government Buildings

2.5

Government Hospitals and nursing home

3.0

 

Setback

Setback is the distance measured from the center of the road ( or from the edge of the road) to the pinth beam of the building.

Importance of setback distance:

1.   It is important for the future widening of the road.

2.   It can be used for the parking of the vehicles.

Also, marginal ditance is the distance measured from the plot boundary to the plinth beam of the building.

Marginal distance are also called side setback or rear ( back) setback.

The  certain setback distance is fixed by government for certain city or areas.



How To Check Quality Of Cement On Site?

Cement is a fine grey powder that, when mixed with water, sets to a hard mass. They possess both adhesive and cohesive properties. They adhere to building units such as bricks, stones, tiles, etc. because of which we are able to make walls and floors of very high strength.


They are considered hydraulic because they set and harden when mixed with water because of the chemical combination of the cement compounds with the water, which yields sub-microscopic crystals or a gel-like material with a high surface area.

 

There are generally two types of cement used on site. They are:

1.   Ordinary Portland cement (OPC): This is the most commonly used cement. This type of cement is manufactured in a powder form by mixing limestone and other raw materials which consists of argillaceous, calcareous, and gypsum. It has adequate resistance to dry shrinkage and cracking, but has less resistance to chemical attack.

It is admirably suitable for use in the place where there is a need for the fast construction and setting time, and where there is no exposure to sulphates in the soil or in the ground.

OPC of different grades attains their maximum strength after 28 days.

OPC is generally used and widely preferred for the construction of high-rise buildings, roads, dams, bridges, flyovers where high strength and fast setting are required.

 

2.   Portland pozzolana cement (PPC): It is an interground blended mixture of cement and pozzolana. Pozzolana is a natural or artificial material containing silica and alumina in a reactive form. These pozzolana materials include volcanic ash burnt clay, fly ash, opaline shales, etc.  

For the manufacture of PPC, about 25% of pozzolanic material is added to the OPC clinkers and gypsums and the mix is thoroughly ground.

They possess higher tensile strength and evolve less heat during the setting. They attain compressive strength with age, due to which they attain less compressive strength in early days.

They are widely used for hydraulic structures such as dams, sewage works, laying concrete underwater, etc. because they impart a higher degree of water-tightness and offer higher resistance to chemical attack and the action of seawater.

 

Generally, we use OPC for constructing our houses and other structures. OPC cement is available in the market in three grades. They are explained below:

1.   OPC-33 grade: For 33-grade cement, 33 means the compressive strength of cement should be 33 N/mm2 (Mpa) after 28 days. This grade of cement is not widely used and can only be recommended for low-strength works like plastering.

 

2.   OPC-43 grade: For 43-grade cement, 43 means the compressive strength of cement should be 43 N/mm2 (Mpa) after 28 days. They are generally used in non-RCC works, wall plastering, and pathways.

 

 

3.   OPC-53 grade: For 53-grade cement, 53 means the compressive strength of cement should be 53 N/mm2 (Mpa) after 28 days. This is a widely used grade of cement and is used in the RCC structures, buildings, pre–stressed concreting, heavy structures, etc.

 

Quality check of cement on site

1.   Manufacturing Date of cement or Packaging Date: There might not be physical changes in cement with time but the strength of cement reduces with age. This is because cement is in the form of powder and it has the property of absorbing moisture from the air quickly. When the cement bag absorbs the moisture from the air, the initial setting takes place and the cement will start to lose its strength gradually.

The cement should have to be used within the 3 months from its manufacturing date. This is because the cement used after 3 months of manufacturing date loses its strength by approximately 20-30%. They lose their strength by 30-40% after 6 months and by 40-50% after 12 months from the manufacturing or production date.


 

2.   Colour test:

The cement should have a uniform grey color with a light greenish shade. Cement color indicates the presence of excessive clay or lime.


3.   Lumps Test:

The sample of the cement must be free from the presence of lumps that are formed due to the absorption of moisture from the atmosphere by the cement. This process is termed hydration.


By inspection and supervision, we can conclude the presence of lumps and the cement bag with lumps should be rejected.

 

4.   Float Test:

Take a hand full of cement and throw it in water, if the cement floats on the surface of the water for some time before sinking, then it is a good quality cement. If the cement sinks immediately, then it is bad quality of cement. Also, if the cement floats on the surface of the water without sinking, then the cement is of bad quality.



5.   Temperature Test:

Cement tends to remain cool when it is in a bag. When we touch the cement from the bag, we feel the presence of cool (cold) in our hands.


 If the cement is cool inside the bag, then the cement is of good quality. If the cement is warm inside the bag, then the process of hydration has already taken place and cement is of bad quality.

 

6.   Rubbing Test for adulteration:

Adulteration is the process of making something poorer in quality by the addition of another substance.

 Take a pinch of cement and rub it within your fingers. If it gives a smooth feeling, then the cement is of good quality.


If it gives a Gritty or rough feeling, then there is an adulteration of silt or sand in the cement and is of bad quality.

 

7.   Setting Test:

Take about 100gm of cement and a small quantity of water and make a stiff paste of it. Then prepare a cement cake with sharp edges and put it on a glass plate and slowly take it underwater in a bucket.




Observing after 24 hours, the cake should remain in its original shape and it should attain some strength, for the cement to be of good quality, as shown in the figure below. The figure shown below is of good quality cement since there are edges.


 

8.   Strength Test:

Prepare a block of 25mm*25mm*200mm from the given sample of cement and immerse the block in water for curing for 7 days.


 Remove the block of cement from water and place it over the support that is 150mm apart and subject the block to a load of 340N (or 34kg weight). If the block does not show any failure, then the cement is of good quality.






What Is a Plinth Beam | Its Necessity And Applications | Description About DPC

      "Plinth" meanings to a lower square base that supports columns, walls, and structures. Plinth beams are reinforced concrete beams that are constructed between walls and foundations. The mechanism of load distribution in any structure is: the load in the structure gets transferred from slabs into a column and from column into the foundation, in the foundation those loads get distributed among the soil.


Why is a plinth beam needed?

1.    For the loads on the walls, all the loads applied on the walls are distributed over the foundation evenly through the plinth beam.

2.    They can join all columns. As, columns are projected upward from the RCC Foundation, and plinth beam joins all the columns right from the foundation.


3.    When the foundation of the structures suffers settlement due to various causes like natural disasters or due to low grade of soil, the plinth beam prevents the expansion or propagation of cracks in the walls above from the foundation.

4.    Plinth beams are the structural element that supports our walls and acts as an element where the walls can rest i.e. it separates the walls from directly laying on the ground.

If we build walls on the soil or on the ground surface, where there is no plinth beam, then it not certain that the ground will hold up the wall. If there is black cotton soil around, then the wall will form various cracks due to the swelling of the black cotton soil under humid conditions. So, a plinth beam is necessary for our structure to be secured.

5.    The plinth beam prevents the entering of moisture into the building from the foundation. For this, DPC is done above the plinth beam.

6.    The plinth beam prevents the building from collapsing during an earthquake, as it splits the superstructure and substructure of the building.


Applications of a plinth beam

1.    Plinth beams must be constructed in high earthquake risk areas.

2.    The most important application of a plinth beam is to withstand outside actions such as water, tree roots, termites, etc. which could affect the life of the plinth.

 

Concrete grade suitable for plinth beam construction

While constructing a plinth beam, the strength of concrete should not be smaller than 20Mpa.

If we are mixing the concrete manually, then an extra of 20% cement needs to be added to the mixture for compensation for the losses.

 

Minimum dimension of a plinth beam

The thickness or depth of the plinth beam should not be smaller than 20 cm, whereas its width should match the width of the final course of the foundation.

 

Important Question:

Q. What do you mean by DPC?

Ans: DPC stands for Damp-proof course. DPC is a horizontal barrier in the wall designed to resist moisture rising through a structure by capillary action.

Usually, bricks also perform capillary action, which causes dampness on the walls, which ultimately causes the plaster of our wall to coat out.




DPC layers can be applied horizontally as well as vertically.

DPC layer is generally laid above the upper surface of the plinth beam or in between the brick masonry built above the plinth beam, which is on the ground floor.




Insulating, plastic, and flexible materials like butyl rubber, hot bitumen, plastic sheets, sheets of lead, copper, cement mortar, etc. are the widely used materials for damp-proofing.

 

 

 

 

 

Definition of mortar | Its Functions And Properties |


Mortar is a paste, which is obtained by mixing binding materials like cement or lime and inert materials or fine aggregates like sand, surkhi, etc. along with water in varying proportions.

Mortar is used as a binding material in stone or brick masonry, or concrete, as a covering material to walls in the form of plasters to provide smooth, hard, and decorative surfaces. So, the strength, durability, and safety of the resulting wall or any structure depend on the quality of the mortar used as a binding medium.

Functions of Mortar:

·       It binds together or provides cohesion between the structural units (like brick, stone, etc.)

·       It forms a homogeneous mass of structure so that it may resist all the loads coming over it and transfer the loads uniformly to its foundation.

·       In all types of concrete, mortar holds coarse aggregates together, so as to form a solid mass.

·        In stone or brick masonry, it fills up empty joints, thus providing cohesion between the consecutive courses of brick. A thin liquid mortar used for such purposes is termed, Grout.

·       It provides a durable/weather resisting layers between different courses of masonry in the structure.

·       Mortar can protect the surface of the brick or stone masonry.

·       To improve the appearance of the structure through plastering. And plastering is one of the methods of applying mortar.

·       It does pointing or plastering to the structure.

(Pointing refers to the finishing of mortar joints in the masonry by covering rough walls and uneven surfaces with a plastic material called plaster, which is also called the mortar.)

 

Properties of a good mortar:

·       The mortar mix should be easily workable in the site condition – easily transported to the place of application.

·       The main quality that mortar should possess is: it should be capable of developing good adhesion to building units (bricks, Stones, etc.)

·       It should be capable of developing sufficient strength in compression, tension, and bond for the work for which it is used.

·       It should possess high durability and should be strong on drying. Also, it should not affect the durability of other materials.

·       It should set quickly so that construction could be accelerated.

·       It should be capable of binding the bricks or stones to give a tight joint through which water cannot penetrate.

·       It should be cheap.

·       Cracks should not be developed in the joints formed by the mortar and should be able to maintain their appearance for a long period.

·       It should possess sufficient plastic property due to which it can be easily placed on the bed of construction in the form of a thin, smooth, and uniform layer.


Mortars are usually named or classified according to the binding material used in their preparation. In general, mortars are classified as follows:

1.    Cement mortars

2.    Lime mortars

3.    Lime-cement mortars

4.    Special mortars

Ø Mud mortars

Ø Cement-clay mortars

Ø Gypsum mortars

Ø Decorative mortars

Ø Packing mortars

Ø Fire resisting mortars

 

Constituents of Brick | Qualities Of a Good Brick | How To Check Quality Of Brick At Site?


Brick is the most essential and commonly used building material. 

How to Check Bearing Capacity of Soil at Site?

 Bearing capacity is the capacity of soil to support or withstand the load applied to the ground.